It has long been recognized that graft copolymers can readily be prepared through the copolymerization of macromolecular monomers (macromers) with conventional small monomers. The instant invention concerns the synthesis of heretofore unknown graft copolymers through the preparation and copolymerization of macromers having terminal (i.e., telechelic) functionalities which are non-identical to each other, thereby forming what shall hereinafter be termed asymmetric polymers. When one such terminal functionality is more reactive than the other, selective chain propagation and/or end group reaction can produce novel polymers. The macromers thus in effect are used as prepolymers for subsequent linear or graft copolymerizations.
To the inventors' knowledge, there are no prior art references describing this type of macromer or the resulting products of its copolymerization. Descriptive of the art of graft copolymerization in general are various published articles and patents. U.S. Pat. No. 3,786,116 describes in broad terms the operation of graft copolymers.
The synthesis of polyisobutylene-based macromers carrying one polymerizable head group such as vinylbenzyl have been described in U.S. Pat. No. 4,327,201 and Polym. Prepr. 23(2),99 (1982), Kennedy and Lo.
These macromer syntheses involve controlled initiation, transferless propagation and controlled termination. The end products however are considerably different from those of the instant invention due to the different mechanism involved, i.e., absence of transfer agent.